utils/math: add a function to return a value somewhere between two numbers

gamecore/utils/math.lua

@@ -50,6 +50,12 @@ function Math.toZero(num, sub)
   end
 end
 
+function Math.between(num, value1, value2)
+  local min = math.min(value1, value2)
+  local max = math.max(value1, value2)
+  return math.min(math.max(num, min), max)
+end
+
 -- VECTOR/DIRECTION functions
 -- Easy-to-use function to handle point and motion